Myocardial perfusion imaging is a noninvasive test for assessing the amount of blood flow to the muscle of the heart, and is used in the diagnosis of myocardial ischemia, myocardial infarction, and coronary heart disease. In the test, a nuclear tracer containing a gamma-emitting radionuclide is injected into the blood stream of a patient, and the tracer is taken up by heart muscle cells that receive good blood flow. The heart is then imaged with a camera that detects gamma rays released by the radionuclide of the tracer, thereby providing an image map of blood perfusion or flow to the heart. Two separate scans of the heart are conducted: a first scan where the heart is at rest and a second scan where the heart is under increased workload (i.e. under stress conditions). The two separate scans are compared to assess whether there are any areas in the heart where blood flow is inadequate under stress conditions, which indicates the presence of a blockage or narrowing in the coronary arteries.
Van Brocklin et al. (United States Patent Application Publication No. 2009/0136424) have previously prepared radiolabelled rotenone derivatives for use as myocardial flow tracers based on their ability to localize in the myocardial tissue of the heart. The number of steps required to synthesize these derivatives, however, may preclude their widespread clinical use in myocardial perfusion imaging. There is therefore a need for radiolabelled rotenone derivatives, which can be easily prepared and which demonstrate sufficient stability to be effectively used in myocardial perfusion imaging.